import math
m=[float(i)for i in input().split()]
x=m[2]-m[0]
y=m[3]-m[1]
print(math.sqrt(float(x*x+y*y))) import math math float(i)for i in input().split() for i in input().split() i input().split() ().split () input split for i in input().split() float(i) float i m=[float(i)for i in input().split()] m [float(i)for i in input().split()] x=m[2]-m[0] x m[2]-m[0] m[2] m 2 m[0] m 0 y=m[3]-m[1] y m[3]-m[1] m[3] m 3 m[1] m 1 print(math.sqrt(float(x*x+y*y))) print math.sqrt(float(x*x+y*y)) math.sqrt math sqrt float(x*x+y*y) float x*x+y*y x*x x x y*y y y y=m[3]-m[1] m[3]-m[1] y m=[float(i)for i in input().split()] [float(i)for i in input().split()] m x=m[2]-m[0] m[2]-m[0] x
import math
m=[float(i)for i in input().split()]
x=m[2]-m[0]
y=m[3]-m[1]
print(math.sqrt(float(x*x+y*y)))